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10 Processing KODAK Motion Picture Films, Module 3, Analytical Procedures • H24.03
For Visual Titration
A. Hypo Index (HI) or Total Reductants:
Where:
B. Thiosulfate (S
2
O
3
=
):
Where:
C. Sodium Sulfite (Na
2
SO
3
):
Where:
HI (1), mL =
(mL Blank A – mL Sample A) (N Na
2
S
2
O
3
)
0.1000 N Na
2
S
2
O
3
HI (1), mL = mL of 0.1000 N I
2
consumed by 1.0 mL
sample
mL Blank A = millilitres of titrant at the end point of the
blank visual titration, Procedure A.
mL Sample A = millilitres of titrant at the end point of the
sample visual titration, Procedure A.
N Na
2
S
2
O
3
= normality of the titrant (meq/mL)
0.1000 = nominal value for the normality of the titrant,
in meq/mL
g/L S
2
O
3
=
=
(mL I
2
)(N I
2
)[eq. wt. S
2
O
3
=
](1000)
(mL Sample size)(1000)
mL I
2
= millilitres of iodine titrant measured at the
visual end point
N I
2
= normality of the titrant (meq/mL)
[eq. wt. S
2
O
3
=
] = equivalent weight of thiosulfate expressed
in mg/meq (112.13)
1000 = factors to convert mg/mL to g/L
g/L Na
2
SO
3
=
[(HI)(N* I
2
)(3)] – [(mL I
2
)(N I
2
)](eq. wt. S
2
O
3
=
)(1000)
(mL Sample size)(1000)
HI = mL of 0.1000 N I2 consumed by 1.0 mL
sample
N* I
2
= nominal 0.1000 normality of iodine used in
the Hypo Index calculation (meq/mL)
3 = conversion of Hypo Index to a 3.0 mL
sample size
mL I
2
= millilitres of iodine titrant measured at the
visual end point, Procedure B
N I
2
= normality of the iodine titrant (meq/mL) used
in Procedure B, visual end point
eq. wt. S
2
O
3
=
= equivalent weight of thiosulfate expressed in
mg/meq (112.13)
mL Sample = sample size used in Procedure B, visual end
point
1000 = conversion factors for milligrams to grams
and milliliters to liters